The invention concerns a forming fabric weave design having two independent woven layers which are interconnected during weaving by a plurality of binder weft yarns. The binder yarns are woven as pairs such that, while a first pair member forms (or completes) the continuous unbroken weave pattern of the of non-binding weft yarns in the paper side (PS) layer, the second member interlaces with at least one warp yarn from the machine side (MS) layer so as to bind that layer to the PS layer. The pair members then exchange position (being directed during weaving from one layer to the other) so that the second member then continues the PS layer weave pattern so that it is unbroken and continuous while the first interlaces with a second, different warp yarn from the MS layer. Each exchange forms a segment of the continuous unbroken PS weave pattern. Such fabrics are known and have been described in U.S. Pat. No. 5,826,627 (Seabrook et al.) and others. Each binder yarn is said to be “intrinsic” in that it contributes to and is part of the PS surface pattern; additionally, each contributes to the interconnection of the PS and MS layers. Fabrics of this type are known as “SSB” or “sheet support binder” type forming fabrics in the papermaking arts.
While satisfactory in many respects, there is always a desire to improve on or provide an alternative to what has been done previously. The present invention is directed to resolving some of the shortcomings of the known prior art fabrics, particularly with respect to fabric stability, increased wear, and ease of seaming, which is typically accomplished by unweaving and reweaving two machine direction (MD) ends together to form a continuous fabric loop without a visible seam.
In the known SSB fabrics, the PS and MS woven layers are interconnected solely by the interweaving of the binder yarns. Each binder yarn of a pair typically interlaces at least once with the yarns of the PS and MS layers in each repeat of the binder weft pattern; each binder yarn also typically forms one segment of the PS weave pattern between exchanges with its pair member. “Binder weft pattern” refers to one repeat of the interweaving pattern of a binder yarn pair used to interconnect the PS and MS layers together as a single fabric construction while forming the PS weave pattern.